Cell Junctions

Question 1

Conventional TEM

Answer 1

Fix and embed tissue
Thin sections
Mount on copper grid
View in EM

Question 2

Freeze-fracture microscopy

Answer 2

Tissue sample in liquid nitrogen (-196 degrees)
Frozen tissue fractured
Gold replica produced over fractured surface
Dissolve tissue and view gold replica under microscope

Question 3

Types of cell junctions

Answer 3

Impermeable/tight junctions
Anchoring
Communicating

Question 4

Tight/impermeable junction proteins

Answer 4

Stops leakages between cells (attaches cells tightly)
Establish membrane/cell surface domains

Question 5

Anchoring junctions

Answer 5

Links cytoskeleton to matrix /between cells
Adherens junctions link actin to cytoskeleton fibre, attachment proteins and transmembrane liner
Desmosomes link intermediate filaments

Question 6

Communicating/gap junctions

Answer 6

Aqueous channels between cells (comms via ions etc)
Functions include communication intracellularly, coordination eg heartbeat or muscle contraction

Question 7

Gap/communicating junction discovery

Answer 7

Electrophysiology:
extraction of cells, separation, micro electrodes added to each cell used to measure voltage or injection of molecules into cells and observe which pass thru